Improving the Reliability of Pile Drivability Studies by Explicitly Simulating Ground Disturbance-Paper

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The paper proposes a framework to improve driven-pile drivability predictions by explicitly simulating how installation disturbs the surrounding ground and how its response may change over time. Conventional drivability analyses use stress-wave theory to estimate pile penetration, stresses and hammer requirements, but often represent installation effects and soil/pile set-up through empirical factors. These factors can be difficult to select and may introduce substantial uncertainty.<br /><br />The proposed method couples one-dimensional stress-wave analysis with independent axisymmetric finite-element models at ground nodes along the pile shaft. Before each impact simulation, these models generate shaft resistance and ground stiffness response curves. During the simulation, pile movements and resistance are exchanged between the pile and ground nodes. Afterward, calculated displacements and interface slip are applied to the finite-element models to update the ground state for subsequent impacts. The framework can also accommodate time-dependent processes. In the demonstration, pile arrival is represented by cylindrical cavity expansion, while a simple elastic-perfectly plastic or strain-softening material model illustrates ground response.<br /><br />Comparisons show that the approach can reproduce the stress-wave response of a conventional continuum model. A strain-softening example also demonstrates how shaft resistance can decline as driving progresses, reducing the simulated number of hammer blows needed to reach the target embedment. These results illustrate the method’s potential, but do not establish its general predictive validity.<br /><br />The framework currently focuses on shaft resistance in closed-ended piles; changes in end-bearing resistance over time are not modeled. Further development is needed to incorporate more realistic soil behavior—such as consolidation, destructuration, cyclic degradation, particle breakage and creep—and to improve representation of pile installation. Validation is also required, particularly for dynamic ground disturbance, large deformations, and finite-element mesh and boundary choices. With these advances, the method could reduce reliance on broad empirical correlations and support more mechanics-based, reliable drivability predictions.

Keywords

driven-pile drivability

stress-wave theory

pile installation

shaft resistance

finite-element models

ground disturbance

soil set-up

cylindrical cavity expansion

strain-softening

hammer blows